Puerarin and Amlodipine Improvement of D-Galactose-Induced Impairments of Behaviour and Neurogenesis in Mouse Dentate Gyrus: Correlation with Glucocorticoid Receptor Expression

Dietary Flavonoids and Adult Neurogenesis: Potential Implications for Brain Aging

Adult neurogenesis deficiency has been proposed to be a common hallmark in different age-related neurodegenerative diseases. The administration of flavonoids is currently reported as a potentially beneficial strategy for preventing brain aging alterations, including adult neurogenesis decline. Flavonoids are a class of plant-derived dietary polyphenols that have drawn attention for their neuroprotective and pro-cognitive effects. Although they undergo extensive metabolism and localize in the brain at low concentrations, flavonoids are now believed to improve cerebral vasculature and interact with signal transduction cascades involved in the regulation of adult neurogenesis. Furthermore, many dietary flavonoids have been shown to reduce oxidative stress and neuroinflammation, improving the neuronal microenvironment where adult neurogenesis occurs. The overall goal of this review is to summarize the evidence supporting the role of flavonoids in modulating adult neurogenesis as well as to highlight how these dietary agents may be promising candidates in restoring healthy brain function during physiological and pathological aging.

Roles of traditional chinese medicine regulating neuroendocrinology on AD treatment

The incidence of sporadic Alzheimer's disease (AD) is increasing in recent years. Studies have shown that in addition to some genetic abnormalities, the majority of AD patients has a history of long-term exposure to risk factors. Neuroendocrine related risk factors have been proved to be strongly associated with AD. Long-term hormone disorder can have a direct detrimental effect on the brain by producing an AD-like pathology and result in cognitive decline by impairing neuronal metabolism, plasticity and survival. Traditional Chinese Medicine(TCM) may regulate the complex process of endocrine disorders, and improve metabolic abnormalities, as well as the resulting neuroinflammation and oxidative damage through a variety of pathways. TCM has unique therapeutic advantages in treating early intervention of AD-related neuroendocrine disorders and preventing cognitive decline. This paper reviewed the relationship between neuroendocrine and AD as well as the related TCM treatment and its mechanism. The advantages of TCM intervention on endocrine disorders and some pending problems was also discussed, and new insights for TCM treatment of dementia in the future was provided.

Prebiotic Agrocybe cylindracea crude polysaccharides combined with Lactobacillus rhamnosus GG postpone aging-related oxidative stress in mice

This study aimed to investigate the potential anti-aging mechanisms of Agrocybe cylindracea crude polysaccharides (APS), when used synergistically with Lactobacillus rhamnosus GG (APS + LGG) in a D-galactose-induced aging mouse model. In the Morris water maze test, APS + LGG showed a significantly higher memory and learning capacity compared to untreated, APS only treated and LGG treated mice. This was thought to be mediated by increased levels of brain-derived neurotrophic factor, which decreased escape latency. In addition to this, in the aging mouse model, APS + LGG co-treatment markedly alleviated liver oxidation and metabolism by enhancing the antioxidant activity of enzymes; this decreased the lipid metabolism and peroxidation levels. Furthermore, high throughput sequencing analysis revealed that an APS + LGG supplemented feed increased the relative abundance of positive bacteria in the gut microbiota such as Alloprevotella and Parvibacter. Importantly, Alloprevotella and Parvibacter showed a negative relationship with low density lipoprotein-cholesterol in the Spearman correlation analysis. These results illustrate that APS, in combination with LGG, postponed aging related oxidative stress when used as a prebiotic. The proposed mechanism for this is the reduction in liver oxidation and lipid metabolism, as well as the regulation of gut microbiota.

The Gut Microbiota Metabolite Urolithin B Improves Cognitive Deficits by Inhibiting Cyt C-Mediated Apoptosis and Promoting the Survival of Neurons Through the PI3K Pathway in Aging Mice

Background: Despite considerable advances in pharmacotherapy, more effective therapeutic interventions for aging-related neurodegenerative disorders (NDs), such as Alzheimer’s disease (AD), remain limited. Urolithin B (UB), one of the major subcategories of urolithins (microbiota metabolites) found in various tissues after ellagitannin consumption, has been shown to possess antioxidant, anti-inflammatory, and antiapoptotic effects. However, the neuroprotective effect of UB on brain aging in mice and its potential mechanisms were still unknown.

Methods: In the current research, we first assessed the ameliorative effects of UB on oxidative injury and apoptosis induced by H₂O₂ in neuro-2a cells. Then a subcutaneous injection of D-galactose in mice for 8 weeks was used to establish the aging model to evaluate the protective effects of UB. The capacity of memory and learning, alterations of hippocampus histology and corresponding molecular mechanisms were all evaluated.

Results: The D-gal-induced accelerated aging model in vivo demonstrated that UB could significantly ameliorate deficits in learning and memory by inhibiting the accumulation of advanced glycation end products (AGEs) and elevating the expression and activity of Cu, Zn-SOD and CAT. Furthermore, UB downregulated the c-Jun N-terminal kinase (JNK) signaling pathway and prevented cytochrome c release from isolated mitochondria, thereby inhibiting neuronal apoptosis during the aging process. More importantly, UB stimulation of aging mice activated ERK and phosphoinositide 3-kinase (PI3K), leading to neuronal survival along with Akt and p44/42 mitogen-activated protein kinase (MAPK) phosphorylation and activation.

Conclusion: In summary, UB effectively alleviated cognitive deficits and ameliorated brain aging-related conditions and could be considered a healthcare product to prevent aging-associated NDs such as AD.

Leonurine ameliorates D-galactose-induced aging in mice through activation of the Nrf2 signalling pathway

Aging is a complex physiological phenomenon associated with oxidative stress damage. The objective of this study was to investigate the potential effects of leonurine on D-galactose-induced aging in mice and its possible mechanisms. In this study, we first tested the antioxidant activity of leonurine in vitro. A subcutaneous injection of D-galactose in mice for 8 weeks was used to establish the aging model to evaluate the protective effects of leonurine. The results showed that treatment with 150 mg·kg^-1 leonurine could improve the mental condition, organic index, and behavioural impairment; significantly increase the activities of antioxidative enzymes including SOD, CAT, and T-AOC; and ameliorate the advanced glycation end product (AGE) level and histopathological injury. Furthermore, the Western blotting data revealed that leonurine supplementation noticeably modulated the suppression of the Nrf2 pathway and upregulated the downstream expression of HO-1 and NOQ1 in aging mice. Additionally, leonurine treatment activated Nrf2 nuclear translocation in both aging mice and normal young mice, and the expression levels of Nrf2 in normal young mice was higher than those in naturally aging mice. In conclusion, our findings suggest that leonurine is a promising agent for attenuating the aging process, and the underlying molecular mechanisms depend on activating the Nrf2 pathway.